Process for waterproofing materials having a fibrous structure and agents used to carry out this process

ABSTRACT

A process is disclosed for waterproofing materials having a fibrous structure, such as leather, persian leather or leather replacement materials, by using waterproofing agents containing sulfosuccinic acid esters. Also disclosed are waterproofing agents used to carry out this process. The sulfosuccinic acid esters are prepared by reacting maleic anhydride with monohydric or polyhydric alcohols, then by sulfitizing them. Reactive siloxanes may also be used as polyhydric alcohols.

The present invention relates to the waterproofing of materials having afibrous structure, in particular leather, fur skins, leathersubstitutes, by using waterproofing agents containing sulfosuccinic acidesters. The invention further relates to waterproofing agents forcarrying out the process. Owing to their mild surfactant character (gooddermatologic compatibility), sulfosuccinic acid esters find increasinguse in shampoos, foam baths and cosmetics (personal care products) wheretheir good emulsifying action, high foaming ability and good detergent,i.e., wetting action is selectively used in general.

The use of sulfosuccinates in the leather manufacture is described inDE-OS 16 69 347 and DE-OS 34 19 405, claiming their use as fatliquorsand greases in the main fatliquoring and in tanning and retanning.

According to DE-OS 35 07 241 the emulsifying properties of sulfosuccinicacid monoesters in combination with impregnating and/or waterproofingfatliquors and greases are utilized to achieve water-repellentproperties of the treated leather; a subsequent fixation with chromiumand/or aluminum salts is carried out resulting in a conversion of thehydrophilic w/o-emulsifier into hydrophobic metal complex salts. Theadditional use of sulfosuccinic acid monoesters in the impregnatingand/or waterproofing fatliquoring serves an intentional stabilityincrease of the fatliquoring emulsion. In addition to the impregnatingfatliquors and greases of the group consisting of oxidized or oxidizedand partially sulfonated C₁₈₋₂₆ -hydrocarbons or C₃₂₋₄₀ -waxes,phosphoric acid mono-C₁₂₋₂₄ -alkyl esters, partial esters ofpolycarboxylic acids, such as citric acid-C₁₆₋₂₄ -alkyl ester, partialesters of polyalcohols, such as sorb and pentaerythritoI-C₁₆₋₂₄ -fattyacid esters, both untreated oils (neutral oils), such as long-chainhydrocarbons, chlorinated paraffin, animal and vegetable oils and fatsor their methyl esters and chlorinated fatty acid methyl esters, andsulfated, sulfited, and/or synthetic fatliquors and greases based onchlorinated paraffin sulfonates may be emulsified or stabilized.

An improvement of the waterproofing action, as against thelast-mentioned process, can substantially be achieved by substitutingthe sulfosuccinic acid monoesters for sulfosuccinic acid monoamides.However, the compulsory subsequent fixation using chromium, aluminum,titanium and/or zirconium salts is still a disadvantage of this processwhich is described in DE-OS 36 20 780. In practice, this fixation ismainly carried out by using chromium salts.

It is known by EP 02 13 480 that the hydrophobing of leather and furs iseffected with a silicone oil and the salt of an N-(C₉ -C₂₀ -acyl) aminoacid used as emulsifier, wherein optional post-treatment with a metallicsalt commonly used in tanning may follow. However, it was found that theomission of the metallic salt fixation leads to insufficientwaterproofing results.

In many countries the regulations with respect to the chromium contentin waste water are becoming increasingly tight. As is generally known, aconsiderable portion of the conventionally used chrome-tanning materialis not bound by the leather fiber and for this reason comes into thewaste water through washing and rinsing processes. Although this portionis lower when highly exhausting chrome tanning agents are used, it isstill above the required and very low values in practice.

Additionally, a process for waterproofing leathers, fur skins andleather substitutes using a carboxyl groups-containing polysiloxanewhose carboxyl groups are present in neutralized form is described in EP03 24 345. This process is conducted in the absence of emulsifiers andwithout aftertreatment using mineral tanning agents.

Accordingly, it is the object of the present invention to providesubstances and procedures which, when applied from the aqueous float,result in waterproof leathers, without having to conduct a subsequenttreatment with mineral salts in order to avoid the above-mentioned wastewater contamination.

This object is achieved by treating chrome-tanned, neutralized andwashed leather with waterproofing agents comprising sulfosuccinic acidmonoester and/or organosilicone monosulfosuccinate. Most surprisingly,it was found that after the acidification an additional metallic saltfixation usual so far can be omitted.

Accordingly, the subject matter of the present invention is a processfor waterproofing materials having a fibrous structure, in particularleather, fur skins and leather substitutes by using waterproofing agentscontaining sulfosuccinic acid monoesters in aqueous float without ametallic salt fixation. An additional subject matter of the presentinvention are waterproofing agents for carrying out this process, whichare based on sulfosuccinic acid monoesters, in particular fatliquoringand greasing waterproofing agents based on special sulfosuccinic acidmonoesters, i.e., organosilicone di-(monosulfosuccinates). Whenorganosilicone di-(monosulfosuccinates) are used as sulfosuccinic acidmonoesters, they may be used alone in waterproofing. Sulfosuccinatesother than organosilicone di-derivatives are combined with mineral oil,paraffin, chloroparaffin, and silicone oil as well as their mixtures andare used as waterproofing agents in this form. The organosiliconedi-(monosulfosuccinates) may not only be used alone, but may also becombined in admixture with other sulfosuccinic acid monoesters and/orother substances having a water-repellent action. These waterproofingagents may be used in both a single-step method instead of the mainfatliquoring and in a multistage method in the pre-fatliquoring, mainfatliquoring and, optionally, top-fatliquoring.

The production of the sulfosuccinic acid monoester salts is carried outby esterification of maleic anhydride with 1 to 2 equivalents ofesterification component. This step is preferably carried out such thatneutral oils are already present during the esterification.Subsequently, reaction of the semi-ester is carried out with 0.5-1.5equivalents of a sulfite or bisulfite, relative to maleic anhydride. Inprinciple, any monohydric or polyhydric alcoholic component having oneor more alkyl residues of the chain length C₁₂ to C₄₀, preferably C₁₆ toC₂₈, as well as wool wax alcohols are suitable for the esterification.They may be saturated or unsaturated, straight-chain or branched. Also,alkoxylated fatty alcohols having ethylene oxide and/or propylene oxideportions of 1-10 moles, preferably 2-5 moles per mole of fatty alcoholand fatty acid monoglycerides and diglycerides, their alkoxylatedproducts, fatty acid polyglycol esters, having ethylene and/or propyleneoxide portions as above, and the pentaerythritol and sorbitan fatty acidesters may be used. Polyols are reacted with the maleic anhydride insuch stoichiometric ratios that per mole of maleic anhydride only onecarboxyl group forms the ester bond.

Reactive siloxanes, e.g., α, ω-organofunctional polysiloxanes of thetype ##STR1## may be used as polyols.

The number of the recurring units n amounts to about 10 to about 30, andm is 1-4.

The preferred neutral oils include mineral oils, paraffins, chlorinatedparaffins, and silicone oils as well as their mixtures, but also animaland/or vegetable oils and fats, such as neatsfoot oil, fish oil, tallow,palm oil, and the like.

By emulsifying the neutral oils with the claimed sulfosuccinates andtheir salts, respectively, a synergistic effect with respect to thewater-repellent finish is achieved. An optimum action is achieved with aneutral oil content of about 25-30%, relative to the total product. Whenmineral oils are used, those based on paraffin have a slightly betteraction than those based on naphthene.

The additional use of silicone oils, e.g., dimethyl polysiloxane,diphenyl polysiloxane, supports the water-repellent properties of theleather, Also, with respect to the feel of the leather this addition isof interest.

To achieve a sufficient emulsion and storage stability hydrophobicemulsifiers may optionally be used in the sulfitation.

In principle, alkali hydroxides, ammonia or alkanolamines are suitablefor the neutralization.

The invention will be illustrated in more detail by the followingexamples in which the usual terms are used:

A.V.=acid value

OH-number=hydroxyl number

All indications in terms of percentage mean percent by weight.

EXAMPLE 1

In a heatable 1.5-l three-neck flask provided with agitator, thermometerand dropping funnel, 127.29 g (0.338 mol) of a technical mixture oflong-chain fatty alcohols C₁₈ -C₂₆ (OH-number: 149) were placed firstand melted at about 60° C. After complete melting, 310 g paraffinicmineral oil and 39.4 g polydimethylsiloxane (viscosity: 350 mPa.s) wereadded and homogenized.

Then the equivalent amount (33.15 g=0.338 mol) of maleic anhydride wasadded. The mixture was stirred to 75° C. for the first hour, and then at85°-90° C. for another hour.

The reaction to the semi-ester was controlled by determination of theacid value (A.V.; 0.65-0.68 mmol/g).

The subsequent sulfitation was conducted at 85°-95° C. with a 25%sulfite solution (48.29 g sodium disulfite, 0.254 mol, corresponding to150% of theory, in 144.9 g water). The addition was effected such thatthe temperature did not fall below 80° C. The total sulfitation wascompleted after 3-4 hours.

By adding 50% sodium hydroxide solution and purified water having atemperature of 60° C., the product is adjusted to a pH of 6.5-7.5 and awater content of approximately 42%.

EXAMPLE 2

In correspondence to Example 1, 101.68 g (0.27 mol) of the fatty alcoholmixture were reacted in 247.7 g paraffinic mineral oil and 31.2 gpolydimethylsiloxane (viscosity: 350 mPa.s) with 26.49 g (0.27 mol)maleic anhydride.

Prior to sulfitation, 23.0 g sulfosuccinic acid monoester based on thefatty alcohol used in Example 1 and reacted with an average of 3 molesof ethylene oxide were added in the form of a 50% aqueousstandardization. The subsequent reaction to the sulfosuccinic acid esterwith a 25% sulfite solution (23.1 g sodium disulfite, 0.12 mol,corresponding to 90% of theory, in 69.3 g water) was conducted as inExample 1.

By adding monoethanolamine and purified water of a temperature of 60°C., the product is adjusted to a pH of 6.5-7.5 and a water content ofabout 50%.

EXAMPLE 3

As in Example 1, 124.28 g (0.33 mol) of a fatty alcohol mixture werereacted in 255.15 g paraffinic mineral oil with 32.27 g (0.33 mol)maleic anhydride.

Prior to sulfitation, 51.0 g of a fatty alcohol C₁₂ -C₁₈ were added. Thesulfitation was conducted under the same outward conditions as inExample 1, however, with a 25% sulfite solution (31.37 g sodiumdisulfite, 0.165 mol, 100% of theory, in 94.1 g water) which had beenadjusted to pH 7 with ammonia liquor.

By adding purified water of 60° C., the product is adjusted to a watercontent of approximately 50%.

EXAMPLE 4

According to Example 1, 127.29 g (0.338 mol) of the fatty alcoholmixture were reacted in 320 g paraffinic mineral oil and 39.4 gpolydimethylsiloxane (viscosity: 350 mPa.s) with 33.15 g (0.338 mol)maleic anhydride.

Afterwards 10 g of the reaction product of oleyl amine and acrylic acidas well as maleic anhydride according to DP-application 36 36 497neutralized with sodium hydroxide solution were added as coemulsifier inthe form of a 25% aqueous emulsion, followed by sulfitationcorresponding to Example 1 with a 25% sulfite solution (48.29 g sodiumdisulfite, 0.254 mol, 150% of theory, in 144.9 g water).

By adding sodium hydroxide solution and water, the product is adjustedto a pH of 6.5-7.5 and a water content of about 39%.

EXAMPLE 5

According to Example 1, 121.87 g (0.467 mol) of a tallow fatty alcohol(OH-number: 215) were reacted in 251.5 g of a paraffinic mineral oilwith 45.81 g (0.467 mol) maleic anhydride.

The sulfitation with a 25% sulfite solution (44.3 g sodium disulfite,0.233 mol, 100% of theory, in 132.9 g water) was effected as in Example1.

By adding monoethanolamine and water, the product is adjusted to a pH of7.0-7.5 and a water content of about 50%.

EXAMPLE 6

As in Example 1, 96.72 g (0.412 mol) of an ethoxylated tallow fattyalcohol having an average of 3 moles of ethylene oxide were reacted in279 g of a paraffinic mineral oil with 40.41 g (0.412 mol) maleicanhydride.

The sulfitation according to Example 1 was carried out with a 25%sulfite solution (39.16 g sodium disulfite, 0.206 mol, 100% of theory,in 117.5 g water).

By adding monoethanolamine and water, the product is adjusted to a pH of7.0-7.5 and a water content of approximately 50%.

EXAMPLE 7

In accordance with Example 1, 142.42 g (0.33 mol) of the same fattyalcohol mixture, however, reacted with an average of 3 moles of ethyleneoxide (OH-number: 130), were reacted in 262 g paraffinic mineral oilwith 32.37 g (0.33 mol) maleic anhydride. The sulfitation as in Example1 was effected with a 25% sulfite solution (31.37 g sodium disulfite,0.165 mol, 100% of theory, in 94.1 g water).

By adding monoethanolamine and water, the product is adjusted to a pH of7.0-7.5 and a water content of approximately 50%.

EXAMPLE 8

In an apparatus as in Example 1, 349.13 g (0.14 mol) of α,ω-hydroxy-organofunctional polydimethylsiloxane (approximately 30dimethylsiloxane units, OH-number: approximately 45) were reacted with27.47 g (0.28 mol) maleic anhydride in correspondence with Example 1.

As coemulsifier, 100 g of the reaction product according toDP-application 36 36 497 (cf. example 4) neutralized and sodiumhydroxide solution were added in the form of a 25% aqueous emulsion.

The sulfitation as in Example 1 was effected with a 25% sulfite solution(26.62 g sodium disulfite, 0.14. mol, 100% of theory, in 79.9 g water).

By adding sodium hydroxide solution and water, the product is adjustedto a pH of 8.0 to 8.5 and a water, content of about 45%.

Application Example 1

The products according to Examples 1-8 were tested with split cattlehide as follows:

Material: fully chrome-tanned split cattle hide

Shaved substance: 1.3-1.4 mm %-indications relative to shaved weight.

    ______________________________________                                        NEUTRALIZATION:                                                                           300%   water 35° C.                                        drain off bath                                                                            150%   water 35° C.                                                    1%     sodium formate undiss.                                                                        10   min                                               1%     sodium bicarbonate 1:10                                                                       60   min                                                      pH: appr. 6                                                drain off bath                                                                WASHING:    300%   water 55° C.                                                                           10   min                                   drain off bath                                                                WATERPROOFING:                                                                            150%   water 55° C.                                                    7.5%   eff. subst. of product                                                                        60   min                                                      acc. to invention 1:4/60° C.                                    1%     formic acid 1:5 20   min                                                      pH: appr. 4.2                                              rinsing:           water 25° C.                                                                           10   min.                                  horse up overnight,                                                           hang up to dry,                                                               moisten, staking.                                                             ______________________________________                                        Examination in the Bally-Penetrometer                                         Example  1      2      3    4    5    6    7    8                             ______________________________________                                        Water penetra-                                                                         >420   185    125  >420 62   50   103  >420                          tion at 10%                                                                   amplitude                                                                     in min.                                                                       Water    17%    28%    25%  11%  26%  36%  32%  11%                           absorption                                                                             after  after  after                                                                              after                                                                              after                                                                              after                                                                              after                                                                              after                                  7 h    4 h    3 h  7 h  1 h  2 h  2 h  7 h                           ______________________________________                                    

Application Example 2 Waterproof glove nappa-natural

Material: Chrome-tanned hair sheep, sammed %-indications relative tosammed weight.

    ______________________________________                                        WASHING:    300%    water 35° C.                                                                         15    min                                   drain off bath                                                                NEUTRALIZATION:                                                                           100%    water 35° C.                                                   1%      sodium bicarbonate                                                                          30    min                                                       1:10                                                                          pH: 6                                                     drain off bath                                                                WASHING:    300%    water 60° C.                                                                         10    min                                   drain off bath                                                                WATERPROOFING:                                                                            100%    water 60° C./                                                  20%     product acc. to                                                                             60    min                                                       Example 1 1:4/60° C.                                           +1.0%   formic acid 1:10                                                                            2 × a 15                                                                      min                                                                     +20   min                                                       pH: appr.                                                                     3.5                                                       rinsing:            water 25° C.                                                                         10    min                                   leather horse up over-                                                        night, vacuum drying                                                          at 60° C./3 min.,                                                      drying in suspended                                                           condition, moisten,                                                           staking, milling.                                                             ______________________________________                                    

Application Example 3

Material: dyed lambskin suede

Float ratio 1:10, relative to dry weight

Subsequent to the dyeing of the fur leather:

    ______________________________________                                        rinsing:                   water 45° C.                                                                      10  min                                 WATERPROOFING:             water 45° C.                                            0.3     g/l    ammonia 1:5                                                                              5   min                                             +8-10   g/l    product acc. to                                                                          90  min                                                            Example 1 1:4/                                                                60° C.                                                  +0.7    ml/l   formic acid 1:5                                                                          30  min                                                            pH of float: appr. 4                               wash:                      water 25° C.                                            0.2     ml/l   formic acid 1:5                                                                          10  min                                 horse up overnight,                                                           centrifuging,                                                                 wet toggling,                                                                 moisten, staking,                                                             carding, shearing                                                             ironing.                                                                      ______________________________________                                    

Soft and fluffy sueded shearlings are obtained having a pronouncedshower proofness.

We claim:
 1. A process of waterproofing a material having a fibrousstructure selected from the group consisting of leather and fur, saidprocess comprising the step of waterproofing said material by treatingsaid material in an aqueous float with a waterproofing agent withoutconducting a mineral salt fixation, said waterproofing agentcomprising:i) an organosilicon di-(monosulfosuccinate) or salt thereof,or ii) a sulfosuccinic acid monoester or salt thereof and at least oneoil selected from mineral oil, paraffins, chlorinated paraffins orsilicone oils.
 2. A process according to claim 1, wherein saidwaterproofing agent consists of an organosilicondi-(monosulfosuccinate).
 3. A process according to claim 1, wherein saidwaterproofing agent comprises a sulfosuccinic acid monoester and atleast one oil selected from mineral oil, paraffins, chlorinatedparaffins or silicone oils.
 4. A process according to claim 1, whereinsaid waterproofing agent further comprises a neutral oil selected frommineral oil, paraffins, chlorinated paraffins, silicone oils, animal andvegetable fats and oils, or mixtures thereof.
 5. A process according toclaim 1, wherein said treating consists of a single stage treatmentcarried out in a main fatliquoring stage.
 6. A process according toclaim 1, wherein said treating consists of a multi-stage treatmentcarried out in a pre-fatliquoring stage, a main fatliquoring stage and atop fatliquoring stage.
 7. A process according to claim 1, wherein saidwaterproofing agent is formed by esterifying maleic anhydride with analcoholic component to produce a maleic acid ester and subsequentlysulfiting the maleic acid ester.
 8. A process according to claim 7,wherein the maleic anhydride is reacted with one or two equivalents ofthe alcoholic component.
 9. A process according to claim 7, wherein saidsulfiting is carried out in the presence of a coemulsified.
 10. Aprocess according to claim 7, wherein said sulfiting is carried out byreacting the maleic acid ester with from 0.5 to 1.5 equivalents of asulfite or bisulfite.
 11. A process according to claim 1, wherein saidwaterproofing agent is formed by sulfiting a monoester of maleic acidwith a monohydric or polyhydric alcohol containing a 12 to 40 carbonatom alkyl residue.
 12. A process according to claim 11, wherein saidalcohol contains a 16 to 28 carbon atom alkyl residue.
 13. A processaccording to claim 1, wherein said waterproofing agent is formed bysulfiting a monoester of maleic acid with wool wax alcohols.
 14. Aprocess according to claim 1, wherein said waterproofing agent is formedby sulfiting a monoester of maleic acid with a fatty alcohol alkoxylatedwith from 1 to 10 moles of ethylene oxide or propylene oxide per mole offatty alcohol.
 15. A process according to claim 14, wherein said fattyalcohol is alkoxylated with from 2 to 5 moles of ethylene oxide orpropylene oxide per mole of fatty alcohol.
 16. A process according toclaim 1, wherein said salt is an alkali, alkaline earth, ammonium, oralkanolamine salt of a sulfosuccinate monoester.
 17. A process ofwaterproofing a material having a fibrous structure selected from thegroup consisting of leather and fur, said process comprising the step ofwaterproofing said material by treating said material in an aqueousfloat with a waterproofing agent comprising an organosilicondi-(monosulfosuccinate) without conducting a mineral salt fixation. 18.Novel sulfosuccinic acid monoesters made by reaction of α,ω-organofunctional polysiloxanes of the formula ##STR2## wherein n is anumber from 10 to 30 and m is 1 to 4, with maleic anhydride andsubsequent sulfitation.